ObjectWriter.java

/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.commons.serialization.serial;

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.NotSerializableException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.IdentityHashMap;

import org.exoplatform.commons.serialization.SerializationContext;
import org.exoplatform.commons.serialization.api.TypeConverter;
import org.exoplatform.commons.serialization.model.ClassTypeModel;
import org.exoplatform.commons.serialization.model.ConvertedTypeModel;
import org.exoplatform.commons.serialization.model.FieldModel;
import org.exoplatform.commons.serialization.model.SerializationMode;
import org.exoplatform.commons.serialization.model.TypeModel;
import org.gatein.common.logging.Logger;
import org.gatein.common.logging.LoggerFactory;

/**
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class ObjectWriter extends ObjectOutputStream {

    /** . */
    private static final Logger log = LoggerFactory.getLogger(ObjectWriter.class);

    /** . */
    private final SerializationContext context;

    /** . */
    private final IdentityHashMap<Object, Integer> objectToId;

    public ObjectWriter(SerializationContext context, OutputStream out) throws IOException {
        super(out);

        //
        enableReplaceObject(true);

        //
        this.context = context;
        this.objectToId = new IdentityHashMap<Object, Integer>();
    }

    private int register(Object o) {
        int nextId = objectToId.size();
        objectToId.put(o, nextId);
        return nextId;
    }

    private void write(Object obj, DataContainer output) throws IOException {
        Class objClass = obj.getClass();
        TypeModel typeModel = context.getTypeDomain().getTypeModel(objClass);

        //
        if (typeModel == null) {
            throw new NotSerializableException("Object " + obj + " does not have its type described");
        }

        //
        if (typeModel instanceof ClassTypeModel) {
            // This is obviously unchecked because of the fact that Object.getClass() returns Class<?>
            // need to find a work around for that
            write((ClassTypeModel) typeModel, obj, output);
        } else {
            write((ConvertedTypeModel) typeModel, obj, output);
        }
    }

    private <O, T> void write(ConvertedTypeModel<O, T> typeModel, O obj, DataContainer output) throws IOException {
        Class<? extends TypeConverter<O, T>> converterClass = typeModel.getConverterJavaType();

        //
        TypeConverter<O, T> converter;
        try {
            converter = converterClass.newInstance();
        } catch (Exception e) {
            throw new AssertionError(e);
        }

        //
        T target;
        try {
            target = converter.write(obj);
        } catch (Exception e) {
            InvalidObjectException ioe = new InvalidObjectException("The object " + obj + " conversion threw an exception ");
            ioe.initCause(e);
            throw ioe;
        }
        if (target == null) {
            throw new InvalidObjectException("The object " + obj + " was converted to null by converter " + converter);
        }

        //
        output.writeInt(DataKind.CONVERTED_OBJECT);
        output.writeObject(typeModel.getJavaType());
        write(target, output);
    }

    private <O> void write(ClassTypeModel<O> typeModel, O obj, DataContainer output) throws IOException {
        if (typeModel.getSerializationMode() == SerializationMode.SERIALIZED) {
            //
            output.writeInt(DataKind.OBJECT);
            output.writeInt(register(obj));
            output.writeObject(typeModel.getJavaType());

            //
            SerializationStatus status = SerializationStatus.NONE;
            for (ClassTypeModel<? super O> currentTypeModel = typeModel; currentTypeModel != null; currentTypeModel = currentTypeModel
                    .getSuperType()) {
                if (currentTypeModel instanceof ClassTypeModel<?>) {
                    for (FieldModel<?, ?> fieldModel : currentTypeModel.getFields()) {
                        if (!fieldModel.isTransient()) {
                            // System.out.println("About to serialize field " + fieldModel + " of type " + currentTypeModel);
                            Object fieldValue = fieldModel.get(obj);
                            if (fieldValue == null) {
                                output.writeObject(DataKind.NULL_VALUE);
                            } else {
                                Integer fieldValueId = objectToId.get(fieldValue);
                                if (fieldValueId != null) {
                                    output.writeObject(DataKind.OBJECT_REF);
                                    output.writeInt(fieldValueId);
                                } else {
                                    output.writeObject(DataKind.OBJECT);
                                    output.writeObject(fieldValue);
                                }
                            }
                        }
                    }
                    switch (status) {
                        case NONE:
                            status = SerializationStatus.FULL;
                            break;
                    }
                } else {
                    if (!currentTypeModel.getFields().isEmpty()) {
                        switch (status) {
                            case FULL:
                                status = SerializationStatus.PARTIAL;
                                break;
                        }
                    }
                }
            }

            //
            switch (status) {
                case FULL:
                    break;
                case PARTIAL:
                    log.debug("Partial serialization of object " + obj);
                    break;
                case NONE:
                    throw new NotSerializableException("Type " + typeModel + " is not serializable");
            }
        } else if (typeModel.getSerializationMode() == SerializationMode.SERIALIZABLE) {
            output.writeInt(DataKind.SERIALIZED_OBJECT);
            output.writeObject(obj);
        } else {
            throw new NotSerializableException("Type " + typeModel + " is not serializable");
        }
    }

    @Override
    protected Object replaceObject(final Object obj) throws IOException {
        if (obj == null) {
            return null;
        }
        if (obj instanceof Serializable) {
            return obj;
        }

        //
        DataContainer output = new DataContainer();

        //
        Integer id = objectToId.get(obj);
        if (id != null) {
            output = new DataContainer();
            output.writeInt(DataKind.OBJECT_REF);
            output.writeObject(id);
        } else {
            write(obj, output);
        }

        //
        return output;
    }
}